An observer moves towards a stationary source of sound with a velocity one-fifth of the velocity of sound. Calculate the percentage increase in the apparent frequency?

Explanation

Here observer moves towards the stationary source.
`v_0 = -v//5,v_s = 0`
Apparent frequency `f. = (v-v_0)/(v-v_s) xx f = (v-v//5)/(v-0) xx f 6/5v = 1.2 v`
The precentage increase in apparent frequency
`(f.-f)/f xx 100 = (1.2f-f)/fxx 100 = 20%`